Efficacy of COVID-19 vaccination campaign in elderly people residing in long-term care facilities: a retrospective observational study from Lombardy region, Italy
More details
Hide details
Università di Pavia via Santa Maria delle Selve, 9 Biassono (MB) 20853 Italy Italy
Università di Milano
Università di Milano Italy
Directorate General for Health, Lombardy Region Italy
Publication date: 2023-04-26
Popul. Med. 2023;5(Supplement):A477
Background and objective:
Prevention Unit from GD Welfare Lombardy evaluated COVID vaccination efficacy among elderly patients who reside in Lombardy long-term care facilities. Aim of the study was to observe the trend of COVID infections and related hospitalizations and deaths in the trimester September-November 2022, in relation to the number of anti-COVID vaccination shots received.

Population included 55,478 patients. Data were extracted from regional disease reporting application “tableau server"". Based on number of inoculations received, patients were stratified and four categories were identified: unvaccinated, vaccinated with less than three doses (patients who did not complete the primary cycle were excluded), vaccinated who received a third dose (1st booster shot), vaccinated who received a fourth dose (2nd booster shot). Only mRNA-based vaccines were employed. For each category, different outcomes were assessed: infection rate, hospitalization rate, mortality rate.

138 out of 521 unvaccinated became infected (26,5%); infection rate in vaccinated resulted 7,3% for patients with primary cycle completed (120/1643), 11,1% for vaccinated with 1st booster shot (1085/9718) and 11,4% among patients who received a 2nd booster dose (4970/43422). Overall infection rate was significantly higher in unvaccinated (26,5%) than vaccinated (0,11%) cohort. Among unvaccinated patients, 6 were hospitalized (1,2%) and 15 died (2,9%). Hospitalization rate in vaccinated was 0,3%, mortality rate 0,5%: in patients with primary cycle completed, 5 hospitalizations (0,3%) and 8 deaths (0,5%) were counted. Hospitalization rate was 0,4% and 0,2%, respectively, in 1st boost (n=35) and 2nd boost cohorts (n=108). Furthermore, mortality rate resulted 0,1% among vaccinated with 1st booster shot (n=67) and slightly increased to 0,4% among 2nd booster group (n=198).

Infection, hospitalization and mortality rates significantly decrease as patients complete at least the primary vaccination cycle. Data confirm the importance of COVID-19 vaccination campaign as prevention tool in elderly patients residing in long-term care facilities.